To usher in a big advance in brain imaging, scientists simply had to cut the fat. By subbing out light-blocking fatty molecules, a new technique turns mouse brains almost fully transparent while retaining their structure and nearly all their important molecules, researchers report in the April 11 Nature.

The new method could help researchers image the whole brain and its circuitry while also doing detailed molecular and cellular analyses, says Clay Reid, a neurobiologist at Harvard Universi...